Abstract: The water conveyance canal in North Xinjiang is a periodic water supply canal, and the "wetting-drying" circulation caused by canal water leakage may significantly reduce the strength of expansive soils and further affect the stability of the expansive soil canals. In order to reduce the threat of canal leakage to the stability of canal slopes, the Construction and Management Department has carried out the transformation of the seepage quick drainage system. Based on this, the stability characteristics of the canals before and after the reform are analyzed through numerical calculation. The results show that if the water level behind the membrane of the leakage section is reduced to 0 m by the vertical drainage well pumping operation, the stability factor of the section under the most dangerous condition is greater than 1.35, which means the canal slope is stable. If the seepage pumping is not carried out, when the section with water level greater than 1 m after membrane is operated for more than 10 years, the stability factor will be less than 1.05, and the canal slope is understable or unstable. Only the function of the vertical drainage wells as the anti-slide piles is analyzed, then the function can be ignored, and the sliding arc will appear in front of the drainage wells. If the location of a drainage well is moves forward, the maximum protection range of a single pile is 44 meters when the drainage well moves to the edge of the canal.